JP7206828B2 - Fixing device and image forming apparatus provided with the fixing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for fixing a toner image transferred to a recording medium onto the recording medium by thermocompression, and an image forming apparatus equipped with the fixing device.

An electrophotographic image forming apparatus includes a fixing device that fixes a toner image transferred to a recording medium such as paper. A fixing device generally includes a belt-shaped fixing member that is heated by a heating member, and a pressure member that is arranged opposite to the fixing member. The toner image is fixed on the recording medium by heating and pressing (thermocompression). In a fixing device that fixes a toner image to a recording medium by such thermal compression, it is necessary to maintain the temperature of the fixing member at a control temperature suitable for thermal fixing.

For example, when a sheet of paper is passed through the nip portion, the temperature of the belt decreases due to the passage of the paper, but the temperature at the nip portion of the fixing member cannot be directly detected. In other words, it is not possible to directly detect the decrease in belt temperature due to the passage of paper. For this reason, in the fixing device described in Japanese Patent Application Laid-Open No. 2002-200001, power correction control is performed by estimating the power consumption based on the thickness of the paper and the like. Specifically, the fixing device detects the temperature of the pressure member, and based on the detected value, the power supplied to the heating member is fixed, which is determined by process conditions such as paper thickness, line speed, and color mode. Control is performed to increase or decrease power based on it.

JP 2017-90663 A

However, in the fixing device described above, the temperature of the fixing member (belt) is controlled by prediction without actually measuring the temperature at the nip portion of the fixing member. The estimated power consumption and the actual power consumption may differ due to the influence of parameters that cannot be grasped, such as variation and paper type. When the predicted power consumption differs from the actual power consumption in this way, the temperature of the fixing member (belt) deviates from the design value, and there is a problem that the temperature ripple of the fixing member increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the deviation of the temperature of the fixing member from the design value and to reduce the temperature ripple of the fixing member.

A fixing device according to an aspect of the present invention includes a belt-like fixing member, a heat source disposed inside the fixing member for heating an inner peripheral surface of the fixing member, and a heat source contacting the heat source to generate a temperature of the heat source. a heat source temperature sensor for detecting a heat source temperature sensor for detecting a pressure member facing the fixing member and forming a nip portion between the fixing member and the recording medium to be fixed is inserted; and the recording medium directed toward the nip portion. a position detection sensor that detects the position of the position detection sensor, an arrival timing determination unit that determines the arrival timing of the leading edge of the recording medium reaching the nip portion based on the detection signal of the position detection sensor, and the heat source temperature sensor a power control unit that calculates a maintenance power for maintaining the detected temperature of the heat source at a predetermined control temperature and supplies the maintenance power to the heat source at the arrival timing; a storage unit for pre-storing ideal transition data indicating an ideal temperature transition of the heat source as time elapses from the arrival timing when the heat source is supplied to the heat source at a timing after the arrival timing; A confirmation timing determination unit that determines a confirmation timing for confirming excess or deficiency based on a detection signal of the position detection sensor or a detection signal of the heat source temperature sensor, and a confirmation timing detected by the heat source temperature sensor at the confirmation timing a correction amount calculation unit that calculates a power correction amount based on a difference between the temperature of the heat source and the temperature at the timing of the confirmation timing in the ideal transition data stored in the storage unit; The power control unit is a fixing device that supplies total power obtained by adding the power correction amount calculated by the correction amount calculation unit and the maintenance power to the heat source.

Further, an image forming apparatus according to another aspect of the present invention includes an image forming unit that forms a toner image, and the fixing device that fixes the toner image formed by the image forming unit onto the surface of the recording medium. and an image forming apparatus.

According to the present invention, deviation of the temperature of the heating member from the design value can be reduced, and temperature ripple of the fixing member can be reduced.

1 is a sectional view showing structures of a fixing device and an image forming apparatus according to an embodiment of the invention; FIG. 1 is a functional block diagram showing electrical configurations of a fixing device and an image forming apparatus according to an embodiment of the invention; FIG. 1 is a sectional view showing the configuration of a fixing device according to an embodiment of the invention; FIG. FIG. 10 is a diagram showing heater temperature, belt temperature, and supplied power in the case of power correction during power shortage; FIG. 10 is a diagram showing the heater temperature, belt temperature, and supplied power in the case of power correction at the time of excess power; 4 is a flow chart showing an example of temperature control processing of the fixing device according to the embodiment of the present invention;

A fixing device and an image forming apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing structures of a fixing device and an image forming apparatus according to an embodiment of the invention. FIG. 2 is a functional block diagram showing electrical configurations of the fixing device and the image forming apparatus according to the embodiment of the invention.

The image forming apparatus 1 is, for example, a multifunction device having multiple functions such as a copy function, a printer function, a scanner function, and a facsimile function. The image forming apparatus 1 includes an apparatus body 11, a document reading section 5, a document feeding section 6, a control unit 10, an image forming section 12, a paper feeding section 14, a fixing section 20, and the like. The image forming apparatus 1 has a fixing device 200 . The fixing device 200 includes a fixing section 20 and an operation control section 100 (particularly, a component of the operation control section 100 that controls the fixing section 20).

The control unit 10 includes a processor, RAM (Random Access Memory), ROM (Read Only Memory), and the like. The processor is a CPU (Central Processing Unit), MPU (Micro-Processing Unit), ASIC (Application Specific Integrated Circuit), or the like.

A control program stored in the ROM or the built-in HDD is executed by the CPU to control the control unit 10. The document reading section 5, the document feeding section 6, the image forming section 12, the paper feeding section 14, and the It functions as an operation control section 100 that controls operations of the fixing section 20 and the like.

The operation control unit 100 includes a power control unit 101 , an arrival timing determination unit 102 , a confirmation timing determination unit 103 , a storage unit 104 and a correction amount calculation unit 105 . Note that the storage unit 104 stores at least various data used in the power control unit 101, the arrival timing determination unit 102, the confirmation timing determination unit 103, and the correction amount calculation unit 105, and information such as formula (1) described later. remembered.

When the image forming apparatus 1 performs a document reading operation, under the control of the operation control section 100 , the document reading section 5 receives the document fed by the document feeding section 6 or placed on the document placing glass 161 . The image of the original document is optically read to generate image data. Image data generated by the document reading unit 5 is stored in a built-in HDD (Hard Disk Drive) or a computer connected to a network.

When the image forming apparatus 1 performs an image forming operation, under the control of the operation control unit 100, the image forming unit 12 converts the image data generated by the document reading operation or the image data stored in the built-in HDD. Based on this, a toner image is formed on a sheet of paper P as a recording medium fed from the paper feeding unit 14 .

When performing color printing, the image forming unit 12M for magenta, the image forming unit 12C for cyan, the image forming unit 12Y for yellow, and the image forming unit 12Bk for black of the image forming section 12 are charged, exposed, and developed. A toner image of each color is formed on the photosensitive drum 121 by the process of . The formed toner images of each color are superimposed on the intermediate transfer belt 125 by the primary transfer roller 126 to form a color toner image. The superimposed color toner images are transferred onto the paper P transported in the transport path 190 by the secondary transfer roller 210 . After the toner image is transferred to the sheet P in this way, the fixing unit 20 performs the fixing process, and the sheet P on which the fixing process is completed is discharged to the discharge tray 151 .

FIG. 3 is a cross-sectional view showing the configuration of the fixing section 20. As shown in FIG. The fixing section 20 includes a fixing roller 21 and a pressure roller 22 as main components. The fixing roller 21 and pressure roller 22 are accommodated in a housing 24 made of resin.

The pressure roller 22 is constructed by providing an elastic layer of silicone rubber on an iron core and coating the outer surface of the elastic layer with a PFA resin film having a thickness of 50 μm. The pressure roller 22 is pivotally supported in the housing 24 so as to be rotatable counterclockwise on the page of FIG. During the fixing process, the rotary shaft 23 of the pressure roller 22 is driven to rotate by a rotary drive section 95 (see FIG. 2) composed of a motor or the like under the control of the operation control section 100 . The pressure roller 22 and the fixing roller 21 form a nip portion N through which the paper P to be fixed is inserted. In addition, the pressure roller 22 is an example of a pressure member in the claims.

The fixing roller 21 includes a belt-like fixing member 211, a heater 212 provided inside the fixing member 211, a heater temperature sensor 213, a holding member 214, a pressing member 215, and the like.

The fixing member 211 is constructed by coating the inner and outer surfaces of a stainless steel belt having an outer diameter of 30 mm and a thickness of 0.03 mm with a fluorine resin. The fixing member 211 is rotatably supported in the housing 24 clockwise in the plane of FIG. The fixing member 211 is pressed against the pressure roller 22 by a pressure member 215 made of a heat-resistant resin pad, and is driven to rotate as the pressure roller 22 rotates. The fixing member 211 forms a nip portion N between itself and the pressure roller 22 arranged to face the fixing member 211 , and fixes the toner image on the paper P inserted in the nip portion N.

Heater 212 is, for example, a ceramic heater. Note that the heater 212 may be a heat source such as an IH heater. The heater 212 performs a heating operation during the fixing process under the control of the operation control unit 100, and stops the heating operation after the fixing process is completed. Note that the heater 212 is an example of a heat source in the claims.

The heater temperature sensor 213 is a contact temperature sensor that contacts the heater 212 and detects the temperature of the heater 212 . The heater temperature sensor 213 outputs a detection signal indicating the temperature value of the heater 212 to the power control section 101 . Note that the heater temperature sensor 213 is an example of a heat source temperature sensor in the claims.

A holding member 214 holds the heater 212 . For example, the holding member 214 holds the heater 212 in a state in which the heater temperature sensor 213 is in contact with the heater 212 in an accommodation recess having a size capable of accommodating the heater 212 .

The fixing device 200 also includes a paper transport guide 191 and a paper position detection sensor 193 . The paper transport guide 191 is a guide member that guides the paper P traveling from the transport path 190 toward the fixing unit 20 to the nip portion N. As shown in FIG. Note that the fixing device 200 according to the present embodiment is described for a case where sheets P of the same predetermined size are fixed.

The paper position detection sensor 193 is a non-contact position sensor that detects the position of the paper P facing the fixing section 20 . The paper position detection sensor 193 is arranged, for example, at a position separated from the nip portion N by a predetermined distance (for example, by one rotation of the fixing member 211) on the upstream side of the paper P transport. The paper position detection sensor 193 outputs a detection signal indicating detection of the paper P to the power control unit 101 . Note that the paper position detection sensor 193 is an example of a position detection sensor in the scope of claims.

The arrival timing determination unit 102 determines the arrival timing at which the leading edge of the paper P reaches the nip portion N based on the detection signal from the paper position detection sensor 193 . For example, the arrival timing determination unit 102 determines that the circumferential length L2 of the fixing member 211 is 80 [mm], the predetermined distance is also 80 [mm], and the predetermined linear velocity V of the fixing member 211 is If it is 100 [mm/s], 0.8 seconds (80 [mm]/100 [mm/s]=0.8 seconds) from the timing when the paper position detection sensor 193 detects the leading edge of the paper P. It is determined that the timing that has passed is the arrival timing at which the leading edge of the paper P reaches the nip portion N. That is, the arrival timing determination unit 102 determines that the time obtained by dividing the distance for one rotation of the fixing member 211 by the linear velocity of the fixing member 211 has elapsed from the timing at which the paper position detection sensor 193 detects the leading edge of the paper P. The timing is determined as the arrival timing.

The power control unit 101 maintains the temperature of the heater 212 detected by the heater temperature sensor 213 at a predetermined control temperature (that is, the fixing temperature). power required to maintain the temperature) is calculated, and the maintenance power is supplied to the heater 212 . The control temperature is determined by the type of toner used, and is, for example, a temperature of 100° C. or higher and 200° C. or lower, which is suitable for fixing (for example, 170° C.).

The storage unit 104 preliminarily stores ideal transition data indicating an ideal temperature transition of the heater 212 when fixing the paper P. FIG. For example, the storage unit 104 stores in advance ideal transition data indicating the transition of the heater temperature indicated by solid lines in FIG. 4 or FIG. 5 to be described later. The ideal transition data of the heater temperature indicated by the solid line in FIG. 4 and the ideal transition data of the heater temperature indicated by the solid line in FIG. 5 are the same data.

The confirmation timing determination unit 103 determines a one-time confirmation timing for confirming the excess or deficiency of power supplied to the heater 212 after the timing at which the leading edge of the sheet P reaches the nip portion N. The determination is made based on the detection signal from the position detection sensor 193 . In the embodiment, the confirmation timing determination unit 103 determines, based on the detection signal from the paper position detection sensor 193, that the time for the fixing member 211 to make one revolution has elapsed from the timing at which the leading edge of the paper P reaches the nip portion N. The timing is determined as a one-time confirmation timing.

Specifically, the confirmation timing determination unit 103 determines that the circumferential length L2 of the fixing member 211 is 80 [mm], the predetermined distance is also 80 [mm], and the linear length of the fixing member 211 is 80 [mm]. Assuming that the speed V is 100 [mm/s], 1.6 seconds ((80 [mm]/100 [mm/s])×2= 1.6 seconds) is determined to be the confirmation timing when the time (80 [mm]/100 [mm/s]=0.8 seconds) for the fixing member 211 to make one revolution has elapsed from the arrival timing.

Note that the confirmation timing determination section 103 may determine that the timing 0.8 seconds after the arrival timing determined by the arrival timing determination section 102 is the confirmation timing. For example, the confirmation timing determination unit 103 determines the timing when the time obtained by dividing the distance for one round by a predetermined linear velocity of the fixing member 211 has elapsed from the arrival timing determined by the arrival timing determination unit 102 . , is determined as confirmation timing.

The correction amount calculation unit 105 calculates the difference between the temperature of the heater 212 detected by the heater temperature sensor 213 at the confirmation timing and the temperature at the timing corresponding to the confirmation timing among the ideal transition data stored in the storage unit 104. to calculate the power correction amount. For example, if the confirmation timing is 0.8 seconds after the arrival timing, the "timing corresponding to the confirmation timing" is 0.8 seconds after the arrival timing in the ideal transition data. It is the timing, and means the same timing as the confirmation timing.

Specifically, the correction amount calculation unit 105 calculates the power correction amount Wcor using the following formula (1).

Wcor = ΔT × Wut = (T def - T) × Wut … (1)

However, Wcor: power correction amount [W], ΔT: temperature difference [°C], Tdef: temperature based on ideal transition data [°C], T: detected temperature of heat source temperature sensor [°C], Wut: power per unit temperature [W/°C].

The correction amount calculation unit 105 calculates, for example, the detection temperature T of the heater temperature sensor 213 (heat source temperature sensor) at the confirmation timing = 150 [°C], and the timing corresponding to the confirmation timing out of the ideal transition data stored in the storage unit 104. When the temperature Tdef = 170 [°C] and the power per unit temperature Wut = 1.1 [W/°C], the power correction amount Wcor [W] is obtained by substituting each numerical value in the above equation (1). be able to. If the power correction amount Wcor is a positive value, it can be seen that the power is insufficient by the positive value.
Power correction amount Wcor = (170 - 150) x 1.1 = 22 [W]
That is, it can be seen that the power of 22 [W] is insufficient.

On the other hand, when the detected temperature T = 190 [°C], the correction amount calculation unit 105 stores the detected temperature T = 190 [°C] of the heater temperature sensor 213 (heat source temperature sensor) at the confirmation timing, for example. Assuming that the temperature Tdef at the timing corresponding to the confirmation timing among the ideal transition data stored in the unit 104 is 170 [°C] and the power per unit temperature Wut = 1.1 [W/°C], the above equation (1) The power correction amount Wcor[W] can be obtained by substituting each numerical value for . If the power correction amount Wcor is a negative value, it can be seen that the power is excessive by the negative value.
Power correction amount Wcor = (170 - 190) x 1.1 = -22 [W]
That is, it can be seen that the power of 22 [W] is excessive.

The power control unit 101 supplies the heater 212 with total power obtained by summing the power correction amount Wcor calculated by the correction amount calculation unit 105 and the maintenance power W. FIG.

Here, power correction by power control section 101 will be described with reference to FIGS. 4 and 5. FIG. FIG. 4 is a diagram showing the heater temperature, the belt temperature, and the supplied electric power in the case of electric power correction when electric power is insufficient. FIG. 5 is a diagram showing the heater temperature, the belt temperature, and the supplied electric power in the case of electric power correction when electric power is excessive.

First, power correction by the power control unit 101 at the time of power shortage will be described. In the case of power shortage, the temperature detection value detected by the heater temperature sensor 213 indicated by the dotted line in FIG. ing. Since the present embodiment does not include a sensor for detecting the temperature of the fixing member 211 (belt temperature), the belt temperature was not actually measured. It is presumed that the value of estimated temperature) has a large falling gradient with respect to the ideal transition data indicating the ideal temperature transition of the temperature of the fixing member 211 (belt temperature) indicated by the solid line in FIG.

Then, the confirmation timing determination unit 103 determines the power change timing (= When it is determined that it is the confirmation timing, that is, the timing after, for example, 0.8 seconds from the start of insertion of the paper P into the nip portion N, the correction amount calculation unit 105 calculates the power correction amount Wcor according to the above equation (1). The power control unit 101 supplies the heater 212 with the total power obtained by adding the power correction amount W cor calculated by the correction amount calculation unit 105 and the maintenance power W. As a result, the rising gradient of the temperature detection value detected by the heater temperature sensor 213 indicated by the dotted line in FIG. The value has reached the target value in the ideal transition data. Looking at the power supply indicated by the dotted line in FIG. 4, the total power obtained by summing the power correction amount Wcor, which is the amount of power that was insufficient at the timing of the leading edge of the paper (=timing of arrival of the paper), and the maintenance power W is shown in FIG. It is supplied to the heater 212 at the power change timing (=confirmation timing). That is, the electric power correction amount Wcor, which is the insufficient electric power to the heater 212, is compensated.

Next, power correction by the power control unit 101 at the time of excess power will be described. In the case of excess power, the temperature detection value detected by the heater temperature sensor 213 indicated by the dotted line in FIG. ing. Since the present embodiment does not include a sensor for detecting the temperature of the fixing member 211 (belt temperature), the belt temperature was not actually measured. It is inferred that the estimated temperature) has a rising gradient, unlike the falling gradient indicated by the ideal transition data indicating the ideal temperature transition of the temperature of the fixing member 211 (belt temperature) indicated by the solid line in FIG. be done.

Then, the confirmation timing determination unit 103 determines the power change timing (= When it is determined that it is the confirmation timing, that is, the timing after, for example, 0.8 seconds from the start of insertion of the paper P into the nip portion N, the correction amount calculation unit 105 calculates the power correction amount Wcor according to the above equation (1). The power control unit 101 supplies the heater 212 with the total power obtained by adding the power correction amount W cor calculated by the correction amount calculation unit 105 and the maintenance power W. As a result, the rising gradient of the temperature detection value detected by the heater temperature sensor 213 indicated by the dotted line in FIG. , the target value in the ideal transition data is reached. Looking at the power supplied indicated by the dotted line in FIG. The total power subtracted from W is supplied to the heater 212 at the power change timing (=confirmation timing) shown in FIG. That is, the power correction amount Wcor, which is the excess power to the heater 212, is deleted.

Here, temperature control processing of the fixing device 200 according to the embodiment will be described with reference to FIG. FIG. 6 is a flowchart illustrating an example of temperature control processing of the fixing device according to the embodiment;

For example, when the image forming apparatus 1 receives a print instruction from a user, the arrival timing determination unit 102 determines whether the arrival timing of the leading edge of the paper P reaches the nip portion N based on the detection signal from the paper position detection sensor 193 . It is determined whether or not (S1). Specifically, the arrival timing determination unit 102 determines that the arrival timing for reaching the nip portion N is 0.8 seconds after the sheet position detection sensor 193 detects the leading edge of the sheet P.

When the arrival timing determining unit 102 determines that the arrival timing is not reached (NO in S1), the arrival timing determination unit 102 returns to S1 and waits for the arrival timing. On the other hand, when the arrival timing determination unit 102 determines that the arrival timing has arrived (YES in S1), the power control unit 101 adjusts the temperature of the heater 212 detected by the heater temperature sensor 213 to a predetermined control temperature. (eg, 170° C.) is calculated, and the maintenance power W is supplied to the heater 212 (S2).

Based on the detection signal from the paper position detection sensor 193, the confirmation timing determination unit 103 determines whether a predetermined time (for example, 0.6 seconds) has elapsed from the timing when the leading edge of the paper P reaches the nip portion N. It is determined whether or not it is the confirmation timing (for example, 0.6 seconds after the start of insertion) (S3).

When the confirmation timing determining unit 103 determines that it is not the confirmation timing (NO in S3), the process returns to S3 and waits for the confirmation timing. On the other hand, when the confirmation timing determination unit 103 determines that it is the confirmation timing (YES in S3), the correction amount calculation unit 105 stores the temperature of the heater 212 detected by the heater temperature sensor 213 at the confirmation timing and the stored temperature. A power correction amount is calculated based on the difference from the temperature at the timing corresponding to the confirmation timing among the ideal transition data stored in the unit 104 (S4). That is, the correction amount calculation unit 105 calculates the power correction amount Wcor using the above equation (1).

The power control unit 101 supplies the heater 212 with the total power obtained by adding the power correction amount Wcor calculated by the correction amount calculation unit 105 and the maintenance power W (S5).

Based on the detection signal from the paper position detection sensor 193, the power control unit 101 determines whether or not it is time for the trailing edge of the paper P to reach the nip portion N (S6). Specifically, the power control unit 101 determines that the timing at which the paper P reaches the nip portion N is the timing 0.8 seconds after the paper position detection sensor 193 detects the trailing edge of the paper P.

If the power control unit 101 determines that it is not the timing for the trailing edge of the paper P to reach the nip portion N (NO in S6), the power control unit 101 returns to S6 and determines that it is the timing for the trailing edge of the paper P to reach the nip portion N. If so (YES in S6), the supply of the maintenance power W for maintaining the heater 212 at the controlled temperature (for example, 170° C.) is terminated (S7).

After S7, the operation control unit 100 determines whether or not printing is finished (S8). The operation control unit 100 determines that the printing is not finished when there is the next printing (NO in S8), proceeds to S1, and executes the above S1 to S7. On the other hand, if there is no next printing, the operation control unit 100 determines that printing is finished (YES in S8), and terminates this process.

According to the fixing section 20 and the image forming apparatus 1 according to the embodiment described above, the paper position detection sensor 193 detects the position of the paper P facing the nip portion N. As shown in FIG. The arrival timing determination unit 102 determines the arrival timing at which the leading edge of the paper P reaches the nip portion N based on the detection signal of the paper position detection sensor 193 . The storage unit 104 preliminarily stores ideal transition data indicating an ideal temperature transition of the heater 212 with the elapsed time from the arrival timing when the paper P is subjected to the fixing process. The confirmation timing determination unit 103 determines confirmation timing for confirming whether the power supplied to the heater 212 is excessive or insufficient, which is the timing after the arrival timing, based on the detection signal of the sheet position detection sensor 193 . The correction amount calculation unit 105 calculates the difference between the temperature of the heater 212 detected by the heater temperature sensor 213 at the confirmation timing and the temperature at the confirmation timing among the ideal transition data stored in the storage unit 104. , to calculate the power correction amount Wcor. The power control unit 101 supplies the heater 212 with total power obtained by summing the power correction amount Wcor calculated by the correction amount calculation unit 105 and the maintenance power W. FIG. As a result, deviation of the temperature of the fixing member 211 from the design value can be reduced, and temperature ripple of the fixing member 211 can be reduced. Further, since it is enough to supply the heater 212 with the total power in consideration of the power correction amount Wcor, it is not necessary to perform temperature feedback control to periodically adjust the temperature detection value to the target temperature, and the control configuration can be simple. can.

Further, the confirmation timing determination unit 103 determines the one-time confirmation timing after the arrival timing based on the detection signal of the sheet position detection sensor 193 . The correction amount calculation unit 105 corresponds to the temperature of the heater 212 detected by the heater temperature sensor 213 at the one-time confirmation timing and the ideal transition data stored in the storage unit 104 at the one-time confirmation timing. A power correction amount is calculated based on the difference between the timing and the temperature. The power control unit 101 supplies the heater 212 with total power obtained by summing the power correction amount Wcor calculated by the correction amount calculation unit 105 and the maintenance power W. FIG. As a result, deviation of the temperature of the fixing member 211 from the design value can be reduced, and temperature ripple of the fixing member 211 can be reduced. Moreover, since only one correction amount control is required, there is no need to perform complicated feedback control, and the temperature ripple of the fixing member 211 can be reduced by simple power control.

Further, since the correction amount calculation unit 105 calculates the power correction amount using the above formula (1), it is possible to accurately calculate the power correction amount.

Further, based on the detection signal of the paper position detection sensor 193, the confirmation timing determination unit 103 determines the timing when the fixing member 211 makes one revolution from the arrival timing as the one-time confirmation timing. That is, the power correction amount is calculated based on the difference between the detected temperature value at the confirmation timing when the fixing member 211 makes one revolution from the arrival timing and the ideal temperature value at the timing corresponding to the confirmation timing among the ideal transition data. For example, when the power correction amount is calculated based on the difference between the detected temperature value and the ideal temperature value at the timing when the fixing member 211 rotates halfway or quarterly from the arrival timing, Due to the influence of thermal conductivity unevenness, an error may occur in the difference, and the power correction amount may become inaccurate. On the other hand, since the power correction amount is calculated based on the difference between the temperature detection value and the ideal temperature value at the timing when the fixing member 211 makes one revolution from the arrival timing, it is possible to prevent errors from occurring in the difference. It is possible to reduce the inaccuracy of the power correction amount. As a result, it is possible to reduce the influence of uneven thermal conductivity within the surface of the fixing member 211, and to accurately calculate the power correction amount.

It should be noted that the present invention is not limited to the configuration of the above embodiment, and various modifications are possible.

<Modification>
In the above-described embodiment, the confirmation timing determination unit 103 determines, based on the detection signal from the sheet position detection sensor 193, the timing when the fixing member 211 completes one rotation from the arrival timing as a one-time confirmation timing. However, it is not limited to this. For example, the confirmation timing determination unit 103 of the fixing unit 20 and the image forming apparatus 1 according to the modification determines the one-time confirmation timing based on the detection signal from the heater temperature sensor 213 (heat source temperature sensor). may be

Specifically, the confirmation timing determination unit 103 determines the temperature of the heater 212 detected by the heater temperature sensor 213 (T: temperature detected by the heater temperature sensor 213 [°C]) and the ideal transition stored in the storage unit 104. The difference (ΔT: temperature difference [°C], ΔT = T def - T) from the temperature indicated by the data (Tdef: temperature based on ideal transition data [°C]) is a predetermined threshold value (e.g., 20°C) is determined as a one-time confirmation timing.

The correction amount calculation unit 105 calculates the power correction amount based on the difference ΔT (that is, the threshold “20° C.”) at the confirmation timing when the difference ΔT reaches the threshold. For example, the correction amount calculation unit 105 calculates the detected temperature T of the heater temperature sensor 213 at the confirmation timing T=150 [° C.], and the temperature Tdef at the timing corresponding to the confirmation timing among the ideal transition data stored in the storage unit 104 Tdef=170 [° C.]. °C] and power per unit temperature Wut = 1.1 [W/°C], the power correction amount Wcor [W] is calculated by substituting each numerical value into the above equation (1).
Power correction amount Wcor = (170 - 150) x 1.1 = 22 [W]
That is, it can be seen that the power of 22 [W] is insufficient.

The power control unit 101 supplies the heater 212 with total power obtained by summing the power correction amount Wcor calculated by the correction amount calculation unit 105 and the maintenance power W. FIG.

In the case of this modification, the confirmation timing determination unit 103 predetermines the difference between the temperature of the heater 212 detected by the heater temperature sensor 213 and the temperature indicated by the ideal transition data stored in the storage unit 104. The timing at which the determined threshold value is reached is determined as a one-time confirmation timing. That is, the power correction amount is calculated based on the difference between the detected temperature value and the ideal temperature value at the one-time confirmation timing when the difference between the detected temperature value and the ideal temperature value reaches the threshold value. As a result, the power correction amount can be calculated accurately, and the power correction can be suitably executed. For example, if the power correction amount is calculated when the difference between the detected temperature value and the ideal temperature value is small (sufficiently smaller than the threshold value), the power correction amount will be inaccurate due to the effects of heat source temperature sensor errors, etc. can be. On the other hand, even if the power correction amount is calculated in a state where the difference between the detected temperature value and the ideal temperature value is large (sufficiently larger than the threshold value), the deviation in temperature becomes very large, and the power correction cannot be made in time. On the other hand, when the difference between the detected temperature value and the ideal temperature value reaches the threshold, the power correction amount is calculated based on the difference between the detected temperature value and the ideal temperature value. can be calculated, and the power correction can be suitably performed.

1 image forming apparatus 10 control unit 12 image forming section 20 fixing section 21 fixing roller 22 pressure roller (pressure member)
100 Operation control unit 101 Power control unit 102 Arrival timing determination unit 103 Confirmation timing determination unit 104 Storage unit 105 Correction amount calculation unit 193 Paper position detection sensor (position detection sensor)

200 fixing device 211 fixing member 212 heater (heat source)
213 heater temperature sensor (heat source temperature sensor)

Claims (4)

a belt-shaped fixing member;
a heat source disposed inside the fixing member for heating an inner peripheral surface of the fixing member;
a heat source temperature sensor that contacts the heat source and detects the temperature of the heat source;
a pressing member disposed opposite to the fixing member and forming a nip portion between the fixing member and the fixing member through which a recording medium to be fixed is inserted;
a position detection sensor that detects the position of the recording medium toward the nip;
an arrival timing determination unit that determines an arrival timing at which the leading edge of the recording medium reaches the nip portion based on the detection signal of the position detection sensor;
a power control unit that calculates maintenance power for maintaining the temperature of the heat source detected by the heat source temperature sensor at a predetermined control temperature, and supplies the maintenance power to the heat source at the arrival timing;
a storage unit for pre-storing ideal transition data indicating an ideal temperature transition of the heat source according to the elapsed time from the arrival timing when fixing the recording medium;
Confirmation timing for determining the confirmation timing after the arrival timing for confirming the excess or deficiency of power supplied to the heat source based on the detection signal of the position detection sensor or the detection signal of the heat source temperature sensor. a determination unit;
A power correction amount based on the difference between the temperature of the heat source detected by the heat source temperature sensor at the confirmation timing and the temperature at the timing of the confirmation timing among the ideal transition data stored in the storage unit and a correction amount calculation unit that calculates
The power control unit supplies total power obtained by adding the power correction amount calculated by the correction amount calculation unit and the maintenance power to the heat source ,
The position detection sensor is arranged at a position separated from the nip portion on a transport upstream side of the recording medium by a distance corresponding to one rotation of the fixing member,
The arrival timing determination unit determines timing when the time obtained by dividing the distance for one round by a predetermined linear velocity of the fixing member has elapsed from the timing when the leading edge of the recording medium is detected by the position detection sensor. is determined as the arrival timing,
The confirmation timing determination unit determines the timing after the time obtained by dividing the distance for one round by a predetermined linear velocity of the fixing member has elapsed from the arrival timing determined by the arrival timing determination unit. Fixing device determined as confirmation timing . a belt-shaped fixing member;
a heat source disposed inside the fixing member for heating an inner peripheral surface of the fixing member;
a heat source temperature sensor that contacts the heat source and detects the temperature of the heat source;
a pressing member disposed opposite to the fixing member and forming a nip portion between the fixing member and the fixing member through which a recording medium to be fixed is inserted;
a position detection sensor that detects the position of the recording medium toward the nip;
an arrival timing determination unit that determines an arrival timing at which the leading edge of the recording medium reaches the nip portion based on the detection signal of the position detection sensor;
a power control unit that calculates maintenance power for maintaining the temperature of the heat source detected by the heat source temperature sensor at a predetermined control temperature, and supplies the maintenance power to the heat source at the arrival timing;
a storage unit for pre-storing ideal transition data indicating an ideal temperature transition of the heat source according to the elapsed time from the arrival timing when fixing the recording medium;
Confirmation timing for determining the confirmation timing after the arrival timing for confirming the excess or deficiency of power supplied to the heat source based on the detection signal of the position detection sensor or the detection signal of the heat source temperature sensor. a determination unit;
A power correction amount based on the difference between the temperature of the heat source detected by the heat source temperature sensor at the confirmation timing and the temperature at the timing of the confirmation timing among the ideal transition data stored in the storage unit and a correction amount calculation unit that calculates
The power control unit supplies total power obtained by adding the power correction amount calculated by the correction amount calculation unit and the maintenance power to the heat source,
The confirmation timing determination unit determines timing when a difference between the temperature of the heat source detected by the heat source temperature sensor and the temperature indicated by the ideal transition data stored in the storage unit reaches a predetermined threshold. is determined as the confirmation timing. The correction amount calculation unit calculates the power correction amount as
Wcor = ΔT × Wut = (T def - T) × Wut … (1)
3. The fixing device according to claim 1, which is calculated using the above formula (1).
However, Wcor: power correction amount [W], ΔT: temperature difference [°C], Tdef: temperature based on ideal transition data [°C], T: detected temperature of heat source temperature sensor [°C], Wut: power per unit temperature [W/°C]. an image forming unit that forms a toner image;
4. An image forming apparatus comprising: a fixing device according to claim 1 , which fixes a toner image formed by said image forming section onto the surface of said recording medium.

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